public class MyLinkeList {
    class ListNode{
        public int val;
        public ListNode next;
        public ListNode(int val){
            this.val=val;
        }
    }
    public class MyLinkedList {
        public ListNode head;

        public void createList(){
            ListNode listNode1=new ListNode(12);
            ListNode listNode2=new ListNode(23);
            ListNode listNode3=new ListNode(34);
            ListNode listNode4=new ListNode(45);
            ListNode listNode5=new ListNode(56);
            listNode1.next=listNode2;
            listNode2.next=listNode3;
            listNode3.next=listNode4;
            listNode4.next=listNode5;
            this.head=listNode1;
        }

        public void display(){
            ListNode cur=head;
            while(cur!=null){
                System.out.print(cur.val+" ");
                cur=cur.next;
            }
            System.out.println();
        }

        //查找单链表中是否包含关键字key
        public boolean contains(int key){
            ListNode cur=head;
            while(cur!=null){
                if(cur.val==key){
                    return true;
                }
                cur=cur.next;
            }
            return false;
        }

        //求单链表的长度
        public int size(){
            int count=0;
            ListNode cur=head;
            while(cur!=null){
                count++;
                cur=cur.next;
            }
            return count;
        }

        //头插法
        public void addFirst(int data){
            ListNode node=new ListNode(data);
            if(head==null){
                head=node;
            }else{
                node.next=head;
                head=node;
            }
        }

        //尾插法
        public void addLast(int data){
            ListNode node=new ListNode(data);
            if(head==null){
                head=node;
            }else{
                ListNode cur=head;
                while(cur.next!=null){
                    cur=cur.next;
                }
                cur.next=node;
            }
        }


        //找到index-1位置的节点地址
        public ListNode findIndex(int index){
            ListNode cur=head;
            while(index-1!=0){
                cur=cur.next;
                index--;
            }
            return cur;
        }
        //任意位置插入
        public void addIndex(int index,int data){
            if(index<0||index>size()){
                System.out.println("index位置不合法");
                return;
            }
            if(index==0){
                addFirst(data);
                return;
            }
            if(index==size()){
                addLast(data);
                return;
            }
            ListNode cur=findIndex(index);
            ListNode node=new ListNode(data);
            node.next=cur.next;
            cur.next=node;
        }


        //找到要删除关键字的前驱
        public ListNode searchPery(int key){
            ListNode cur=this.head;
            while(cur.next!=null){
                if(cur.next.val==key){
                    return cur;
                }
                cur=cur.next;
            }
            return null;
        }

        //删除第一次出现关键字为key的节点
        public void remove(int key){
            if(head==null){
                System.out.println("单链表为空，不能删除！");
                return;
            }
            if(head.val==key){
                head=head.next;
                return;
            }
            ListNode cur=searchPery(key);
            if(cur==null){
                System.out.println("没有要删除的节点！");
                return;
            }
            ListNode del=cur.next;
            cur.next=del.next;
        }

        //删除所有值为key的节点
        public ListNode removeAllKey(int key){
            if(head==null) return null;
            ListNode prev=head;
            ListNode cur=head.next;
            while(cur!=null){
                if(cur.val==key){
                    prev.next=cur.next;
                    cur=cur.next;
                }else{
                    prev=cur;
                    cur=cur.next;
                }
            }
            if(head.val==key){
                head=head.next;
            }
            return head;
        }

        public void clear(){
            while(head!=null){
                ListNode curNext=head.next;
                head.next=null;
                head=curNext;+-
            }
        }

        public static void main(String[] args) {
            MyLinkedList myLinkedList=new MyLinkedList();
            //myLinkedList.createList();
            myLinkedList.addFirst(23);
            myLinkedList.addFirst(34);
            myLinkedList.addFirst(45);
            myLinkedList.addFirst(56);
            myLinkedList.addLast(3);
            myLinkedList.display();
            myLinkedList.remove(3);
            myLinkedList.display();
            System.out.println(myLinkedList.contains(56));
            System.out.println(myLinkedList.size());;
        }

    }

}
